1. Field of the Invention
The present invention relates to an intake air control system for a V-type internal combustion engine. More particularly, the present invention relates to an intake air control system for a V-type engine in which electrically-operated throttle actuators are situated at an upper portion of a space defined between banks of the V-type engine.
2. Description of the Background Art
Conventionally, in an intake air control system of a V-type internal combustion engine, a throttle valve, for controlling a flow rate of intake air in an intake passage, is provided within a throttle body. Such throttle valve is driven by an electrically-operated actuator based on a throttle manipulation quantity. The electrically-operated actuator is arranged in a V-shaped space defined between two banks of the V-type internal combustion engine. An example of such configuration of the electrically-operated actuator(s) is disclosed in the Japanese patent document number JP-A-2002-256900.
According to the Japanese patent document JP-A-2002-256900, the V-shaped space, which is formed between two banks of the V-type engine, is a space in which various kinds of auxiliary equipments or the like of the internal combustion engine are arranged.
Accordingly, in an attempt to arrange the electrically-operated actuator for driving the throttle valve in the V-shaped space, it is necessary to take measures which will not impose restriction on the arrangement of the auxiliary equipments.
Further, since the V-shaped space is formed between two banks of the V-type engine, which are heated due to combustion activity in the cylinders, the V-shaped space is liable to be easily filled with hot air. Therefore, it is necessary to take measures to prevent the electrically-operated actuator, especially, a drive motor thereof from being excessively thermally influenced by the hot air from the engine for enhancing the durability thereof. However, the intake system structure described in the patent document JP-A-2002-256900 fails to take the above-mentioned measures into consideration.
Accordingly, the present invention has been made under such circumstances. It is an object of the present invention to provide an intake air control system for a V-type internal combustion engine which ensures a space for arranging existing auxiliary equipments or the like in a V-shaped space, and facilitates cooling of an electrically-operated actuator situated in the V-shaped space, thereby enhancing the durability of the electrically-operated actuator.